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Assessing the antifungal activity of various sources of sodium lignosulfonate and chitosan against fungi isolated from spoiled hay.

A. Y. Leon-Tinoco

Abstract:

248
Assessing the antifungal activity of various sources of sodium lignosulfonate and chitosan against fungi isolated from spoiled hay.
A. Y. Leon-Tinoco*1, S. L. Annis1, S. T. R. Almeida2, B. C. Guimar�es2, R. Hollandsworth1, A. Poulin1, K. Dean1, M. Killerby1, C. Wu3, A. Lichtenwalner1, B. Perkins1, D. Skonberg1, Z. X. Ma4, R. Causey1, J. J. Romero1. 1University of Maine Orono, ME, 2University of Lavras Lavras, MG, Brazil, 3University of Delaware Newark, DE, 4University of Florida Gainesville, FL.

Our objective was to assess the antifungal activity of a collection of 4 sodium lignosulfonate [Sappi (NaSP), Sigma-Aldrich (NaAL), Beantown (NaBT), and Spectrum (NaUM)] and 2 chitosan [naive (ChNv) and microparticles (ChMp)] sources. We determined their minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) against Aspergillus amoenus, Mucor circinelloides, Penicillium solitum, and Debaromyces hansenii at pH 4 and 6 using malt-extract broth and agar. Propionic acid (PRP) was the positive control. The MIC and MFC assays were carried out in duplicate in each of 3 independent runs. Across lignosulfonates, NaSP was the most effective inhibitor and fungicide at pH 4 (Table 1), except for M. circinelloides. At both pH 4 and 6, PRP was more antifungal than NaSP, which had no activity at pH 6. Except for M. circinelloides, ChNV and ChMp were more effective at killing than lignosulfonates and PRP at both pH 4 and 6. In conclusion, NaSP was the most antifungal lignosulfonate tested. Despite not inhibiting all fungi tested, chitosans had the strongest antifungal activity when effective. Results warrant their development as potential hay preservatives.Table 1. Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values (mg/mL � SD) of compounds tested against fungi isolated from spoiled hay as a function of media pH

CompoundpHA. amoenusP. solitumM. circinelloidesD. hansenii
MICMFCMICMFCMICMFCMICMFC
NaSP416.0�4.229.0�2.215.0�0.031.0�5.515.0�0>6013.8�2.513.8�2.5
6>60n.c.1>60n.c.>60n.c.>60n.c.
NaAL4n.d.2>60n.d.>60n.d.>60n.d.20.0�0
6>60n.c.>60n.c.>60n.c.>60n.c.
NaUM4>60n.c.>60n.c.>60n.c.58.3�2.9>60
6>60n.c.>60n.c.>60n.c.>60n.c.
NaBT4n.d.38.6�2.4n.d.40.0�0n.d.45.0�0n.d.28.8�2.5
6>60n.c.>60n.c.>60n.c.>60n.c.
ChMp4n.d.5.1�1.1n.d.1.6�0.9>8n.c.0.07�0.020.16�0.0
6n.d.2.9�0.7n.d.0.06�0.02>8n.c.0.08�0.00.67�0.28
ChNv4n.d.1.9�0.7n.d.2.3�0.9>10n.c.0.02�0.00.04�0.0
6n.d.1.1�0.7n.d.2.2�0.6>10n.c.0.02�0.00.07�0.02
PRP41.25�0.07.5�2.02.5�0.05.0�0.03.3�0.018.8�2.51.25�0.02.5�0.0
612.0�2.7>6016.3�4.8>6012.5�2.9>6014.0�2.215.0�0.0
1n.c. = not calculated.2n.d. = cannot be determined visually.

Keywords: spoilage, lignosulfonates, chitosan.